Method and apparatus for applying a coating material

ABSTRACT

A vertically orientated preheated article such as a fibrocement pipe is coated by contact with powdered resinous material. The powder is placed on top of a horizontal screen, vacuum is applied to the back side to hold the powder to the screen and then the screen is tilted vertically and moved into contact with the vertical article to deposit the coating.

United States Patent [72] Inventor Leonard Irving Daniel Flagtown, N.J.

Dec. 29, 1966 Nov. 2, 1971 Johns-Manville Corporation New York, N .Y.

211 Appl. No. [22] Filed [45] Patented [73] Assignee [54] METHOD AND APPARATUS FOR APPLYING A 3,232,190 2/1966 Willmott l17/17.5 X 3,375,806 4/1968 Nost 117/l7.5 X 2,341,732 2/1944 Marvin 117/22 2,844,489 7/1958 Gemmer 7/21 X 3,032,816 5/1962 Zimmerli 117/21 X 3,102,043 8/1963 Winthrop et al 1 17/21 3,106,769 10/1963 Goethe et a1. 117/21 X 3,245,341 4/1966 Childress et a1. 117/17.5 X 3,247,004 4/1966 Dosser 1 17/21 X 3,377,183 4/1968 Hurt et al.... 117/21 X 3,377,202 4/1968 Belove.... 117/22 X 3,459,578 8/1969 Laulan 117/18 3,470,010 9/1969 Christiansen 117/18 Primary Examiner-William D. Martin Assistant Examiner Edward J. Cabic Attorneys-John A. McKinney and Robert M. Krone ABSTRACT: A vertically orientated preheated article such as a fibrocement pipe is coated by contact with powdered resinous material. The powder is placed on top of a horizontal screen, vacuum is applied to the back side to hold the powder to the screen and then the screen is tilted vertically and moved into contact with the vertical article to deposit the coating.

PATENTEnrmvz? 1971 3.617327 INVENTOR.

Maweo [mm DAN/4 BY METHOD AND APPARATUS FOR APPLYING A COATING MATERIAL This invention relates to a resin-coated article, such as fibrocement pipe, and is particularly directed to method and apparatus for providing a coating of resinous material on surfaces which extend generally perpendicular to the horizontal while being coated. While theinvention is disclosed particularly with reference to applying a resinous coating material to a fibrocement pipe, the inventive concepts may be useful in the application of a resinous coating material to any article.

When applying a resinous coating material to the surface of an article, such as a fibrocement pipe, it is customary to support the pipe with its longitudinal axis lying substantially in a horizontal plane. It has been found extremely difficult to coat a surface extending generally in a plane perpendicular to the horizontal such as the surface defining the axial extremity of the fibrocement pipe. While many systems have been offered to provide a coating on these surfaces, the proposed systems have not been satisfactory. In some instances, the systems require an additional handling of the pipe and therefore, add to the cost of its production. In other instances, the coating applied to the end surface is not of uniform depth and therefore does not provide the necessary protection at all areas.

It is a primary object of the instant invention to provide a system for applying a resinous coating material to a surface which necessarily extends generally in a vertical plane during a coating operation so as to form a continuous coating of substantially uniform thickness thereon.

the foregoing object is accomplished in accordance with the instant invention by a system wherein a quantity of dry, powdered resinous coating material is supported in a vertical plane and moved into contact with the surface of the ARTICLE to be coated, such as the end surface defining the axial extremity of a fibrocement pipe. The pipe is at a temperature greater than the melting-point temperature of the powdered resinous coating material and has been positioned with its longitudinal axis in a horizontal plane as part of a process wherein its inner surface is coated with a resinous coating material by a system that forms no part of the present invention. The aforementioned contact between the hot end surface of the pipe and the powdered resinous coating material is maintained until a sufficient quantity of the powdered resinous coating material has been melted to form a coating of desired thickness on the end surface of the pipe.

The invention will be more fully understood and further objects and advantages thereof will become apparent when reference is made to the following detailed description of a preferred embodiment of the invention and the accompanying drawings in which:

FIG. 1 is a pictorial representation of a portion of the apparatus of the instant invention;

FIG. 2 is a view in cross section taken on a plane passing the line of 2--2 ofFlG. l; and

FIG. 3 is a side elevation illustrating schematically the operation of the coating system of the instant invention.

Referring to the drawing and in particular to FIG. 1, there is illustrated a box 2 having a base 4 and four connected sidewalls 6. The top 8 of the box 2 is open to provide a passageway of the article to be coated such as the end portion of a fibrocement pipe as described below. A screen 10 is mounted within the box 2 so as to be secured to the side walls 6 in a fluidtight relationship and is positioned generally parallel to the base 4. The screen 10 is formed from material which is air-permeable but opaque to finely divided particles of a dry, powdered resinous material for a purpose to be described. A cavity 12 defined by the base 4, the screen 10, and the sidewalls 6 is connected by suitable means such as the flexible pipe I4 to a vacuum source (not shown).

In FIG. 3, there is illustrated schematically the operation of the coating system of the instant invention to apply a coating to the end surface defining the axial extremity of a fibrocement pipe. As illustrated, a fibrocement pipe 16, such as an asbestos-cement pipe, is supported on a rotatable means 18,

such as a pair of spaced rollers, so that the longitudinal axis of the pipe 16 lies generally in a horizontal plane. A box 2 of the type illustrated in FIGS. 1 and 2 is pivotally mounted by means 20 to a carriage 22 which carriage may be moved in a horizontal plane toward and away from the means 18 supporting the pipe 16 as indicated by the arrow 24.

In operation, a box 2 mounted on the carriage 22 is positioned so that the screen 10 lies generally in a horizontal plane as indicated in the dotted outline of FIG. 3. A quantity of resinous coating material in dry, powdered form is deposited upper the UPPER surface of the screen 1) to a substantially uniform depth such as between about one-eighth to onefourth inch. The vacuum source is then activated so as to hold the resinous coating material in deposited position on the screen 10. Tl-le box 2 is then pivoted about the means 20 so that screen 10, with the resinous coating material thereon held in deposited position by the vacuum 20, lies generally in a vertical plane. The box 2 is then moved by the carriage 22 toward the pipe 16 until the end surface 26 defining the axial extremity of the pipe 16 is in contact with the resinous coating material on the screen 10. The pipe 16, which has been raised in a separate operate to a temperature high enough to melt the resinous coating material, gradually melts the powdered resinous coating material contacted by its hot end surface 2651.

to form a coating thereon. The end surface 26 is maintained in contact with the resinous coating material for a time sufiicient to form a coating of the desired thickness. Since the temperature of all points of the end surface 26 is substantially even and since all portions of the end surface 26 contact the resinous coating material for the same length of time, the coating formed on the end surface 26 is extremely uniform in all aspects. The resinous coating material is selected so as to have a viscosity which is great enough so that it is self supporting with no flow characteristics when in melted form on the end surface 26 of the pipe 16 even when the end surface is in a vertical plane as illustrated in FIG. 3.

In one operation, a 6 -inch asbestos-cement pipe having a wall thickness of 0.58 inch was raised to a temperature of about 400 F. and placed on a pair of rollers so that its longitudinal axis was lying generally in a horizontal plane. A dry,

powered resinous coating material comprising a polyethylene resin of the type marketed by U.S. Industrial Chemicals Company under the trade designation MN 710 and having a particle size between about 20 and mesh was deposited on a screen 10 in a box 2 having a square opening 8 greater than 6 inches on each side. A vacuum of 8 of 14 inches. Hg was set up in the box 2 to hold the deposited resinous coating material in position on the screen 10, and the box was then rotated so that the screen 10 extended generally in a vertical plane. The box was moved toward the pipe 16 so that the end surface on the pipe was contacted by the resinous coating material on the screen 10. The contact between the resinous coating material and the end surface of the pipe was maintained for 5 seconds to form a uniform coating on the end surface of the axial extremity of the pipe of approximately 20 mils in thickness. The box was then moved away from the pipe so that additional operations could be performed on the pipe. If a thicker coating had been desired, the contact between the end surface of the pipe and the resinous coating material on the screen would have continued for a longer period of time.

While the invention has been described in relation to the formation of a coating on the end surface of a fibrocement pipe, it will be understood that the inventive concepts may be used with other articles and that the steps described need not be strictly adhered to and various changes and modifications may suggest themselves to one skilled in the art, all falling within the scope of the invention as defined by the subjoined claims.

What I claim is:

1. A method for applying a coating material to a surface of an article while the surface to be coated is lying generally in a vertical plane comprising;

a. supporting an article which is at a temperature greater than the temperature at which a dry, powdered coating material will melt, with the surface thereof to be coated lying generally in a vertical plane,

b. forming a layer of said coating material in dry, powdered form on screen means disposed in a generally horizontal plane.

c. maintaining the coating material on the screen by holding a vacuum on the other side of the screen means while tilting the screen means to a generally vertical plane and moving it against the surface to be coated,

d. forming a layer of coating on the vertical surface of the article by heat of the article melting a portion of the layer of coating material.

2. The method of claim 1 further defined by forming said layer of dry powdered coating material from a polyethylene resin in particulate form having a particulate size between about 20 and I mesh.

3. Apparatus for applying a coating material to a surface of an article while the surface to be coated is lying generally in a vertical plane comprising;

a. means for maintiaining an article which is at a temperature at which a dry, powdered coating material will melt,

in a position with at least the surface thereof to be coated lying generally in a vertical plane,

b. a container having vertically disposed screen means on which said dry, powdered coating material is retained,

c. said container having a passageway on one side of said screen across which the surface to be coated may pass and having means on the other side of said screen for receiving a vacuum to holding said dry powdery coating material in deposited position on said screen,

d. means for moving said vertical layer of coating material into contact with the surface to be coated, and

e. means for maintaining said contact until a sufficient quantity of said dry, powdered coating material has been melted to form a coating of a desired thickness on said generally vertical surface.

4. Apparatus as defined in claim 3 and further comprising:

means supporting said container so that it may be positioned with said screen in a generally horizontal plane or in a vertical plane generally parallel to said generally vertical surface to be coated.

5. Apparatus as defined in claim 3 further defined by said container being adapted for being disposed in one position with said screen substantially horizontal for receiving said coating material thereover and being adapted for movement to another position with said screen substantially vertical for movement toward the surface to be coated.

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2. The method of claim 1 further defined by forming said layer of dry powdered coating material from a polyethylene resin in particulate form having a particulate size between about 20 and 100 mesh.
 3. Apparatus for applying a coating material to a surface of an article while the surface to be coated is lying generally in a vertical plane comprising; a. means for maintiaining an article which is at a temperature at which a dry, powdered coating material will melt, in a position with at least the surface thereof to be coated lying generally in a vertical plane, b. a container having vertically disposed screen means on which said dry, powdered coating material is retained, c. said container having a passageway on one side of said screen across which the surface to be coated may pass and having means on the other side of said screen for receiving a vacuum to holding said dry powdery coating material in deposited position on said screen, d. means for moving said vertical layer of coating material into contact with the surface to be coated, and e. means for maintaining said contact until a sufficient quantity of said dry, powdered coating material has been melted to form a coating of a deSired thickness on said generally vertical surface.
 4. Apparatus as defined in claim 3 and further comprising: means supporting said container so that it may be positioned with said screen in a generally horizontal plane or in a vertical plane generally parallel to said generally vertical surface to be coated.
 5. Apparatus as defined in claim 3 further defined by said container being adapted for being disposed in one position with said screen substantially horizontal for receiving said coating material thereover and being adapted for movement to another position with said screen substantially vertical for movement toward the surface to be coated. 